# std::allocation_result

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< cpp‎ | memory

Defined in header `<memory>` |  |
template< class Pointer, class SizeType = std::size_t > struct allocation_result; |  | (since C++23)

`allocation_result` specializations are returned from the `allocate_at_least` member function of appropriate Allocator types (e.g. `std::allocator::allocate_at_least`) and `std::allocator_traits::allocate_at_least`.

Every specialization of `allocation_result` has no base classes or declared members other than `ptr` and `count`, thus it is suitable for aggregate initialization and structured binding.

### Template parameters

Pointer | - | typically std::allocator_traits<Alloc>::pointer, where `Alloc` is an Allocator type
SizeType | - | typically std::allocator_traits<Alloc>::size_type, where `Alloc` is an Allocator type

### Data members

Member name | Definition
ptr | a pointer of type `Pointer` which is typically used for the address of the first element in the storage allocated by `allocate_at_least` (public member object)
count | a value of type `SizeType` which is typically used for the actual number of elements in the storage allocated by `allocate_at_least` (public member object)

### Notes

`Pointer` and `SizeType` are a pointer to an object type and std::make_unsigned_t<std::ptrdiff_t> (which is almost always same as std::size_t) by default.

Feature-test macro | Value | Std | Feature
--- | --- | --- | ---
`__cpp_lib_allocate_at_least` | `202302L` | (C++23) | Size-feedback in the Allocator interface

### Example

| This section is incomplete Reason: no example

### See also

allocate_at_least (C++23) | allocates uninitialized storage at least as large as requested size (public member function of `std::allocator<T>`)
allocate_at_least [static] (C++23) | allocates storage at least as large as the requested size via an allocator (public static member function of `std::allocator_traits<Alloc>`)

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